1. Field of the Invention
The present invention relates to centrifugal machines and more particularly (since it is in that case that its application appears to present the greatest interest), but not exclusively, to centrifuging machines of the pendulum type intended for the reprocessing of radio-active materials.
2. History of the Related Art
As illustrated in FIG. 1 of the accompanying drawings, such a machine generally comprises a lower bowl 1 which is disposed inside a fixed containment envelope or housing 2 and which is secured to the base of a vertical shaft 3 driven in rotation by a motor 4 with the interposition of a pivot system 5 which allows the assembly to be oriented freely under the effect of the unbalances created by the high-speed rotation of the bowl 1. In order to allow extraction of the rotating assembly for operations of maintenance, repair or replacement, the shaft 3 passes through the protective slab or shield 6 which supports the fixed envelope 2 through a removable stopper 7 which is itself secured to an inner tank 8 for supplying the rotating bowl 1.
In the conventional art, the laden liquid is poured into the tank 8 via a pouring spout 9 mounted to slide telescopically on the end of the supply pipe 10. Axial displacement of the spout 9 under the effect of a control mechanism 11 supported either by the slab 6 or by a removable stopper 12 engaged in a vertical housing or opening therein, makes it possible in one direction to bring the free end of the spout 9 above the interior of the tank 8, avoiding any risk of untimely flow of the laden liquid in the lower part of the envelope 2 at the level of which the purified liquid is collected and evacuated (pipe referenced 13), while the slide of this spout 9 in the opposite direction allows withdrawal of the spout 9 upwardly with the assembly supported by the removable stopper 7.
When the laden liquid to be processed is radioactive or otherwise dangerous, it is essential to avoid any risk of leakage of liquid, gaseous release or of radiations at the level of the connection between the retractable spout 9 and the end of the pipe 10. To that end, a deformable metal bellows element 14 is generally employed which ensures containment of the connection without hindering axial sliding of the spout 9.
Now, in practice, production of this bellows element 14 raises problems which are difficult to solve. If its thickness is too small, it may be damaged very rapidly by mechanical shock or by corrosion, in that case creating the leakages which is to be avoided, while, if this thickness is provided to be sufficiently large to set aside such a drawback, it becomes difficult to manoeuvre the control mechanism 11 associated with the spout 9. This leads to risks of errors of positioning of the spout or to failures. A compromise must therefore be adopted which does not satisfy either one or the other of the two imperatives.
It is an object of the present invention to solve the problem by purely and simply eliminating the protective metal bellows element conventionally associated with the pouring spout.